长江中下游及邻区基底和花岗岩成矿元素丰度背景的研究

本文系统地研究了长江中下游及邻区的结晶基底,褶皱基底及花岗岩岩基成矿元素丰度背景,从而为区域Ｃｕ、Ａｕ,Ｗ、Ｓｎ等成矿作用提供了一套完整的基础地球化学数据,用此来作为窥视地壳组成及成矿作用时空演变的窗口。     

内蒙古中南部出露地壳元素丰度值的估算

运用区域大规模采样方法,对内蒙古中南部地区所采样品进行元素丰度值加权计算,这是建立区域地壳模型的基础工作之一,同时也为化探异常的检出提供较为准确的背景值。研究区涉及内蒙古地轴和内蒙古中部造山系2个构造单元。采用加权求平均值的方法,得到内蒙古中南部出露地壳10种常量元素氧化物和40种微量元素的丰度值。经地表热流值、地震平均波速和元素比值方法检验后证明所得结果合理。计算所得内蒙古中南部出露地壳平均成分为花岗闪长质,与目前一般认为的结论相同。将结果与其他地区进行比较分析后可知,内蒙古中南部出露的地壳与全球上地壳的组成基本一致。由微量元素、稀土元素的图解和内蒙古中南部出露地壳的元素丰度与中国东部出露地壳元素丰度的对比可以看出,整体上,内蒙古中南部具有较强的壳内分异作用和地壳增生作用(地幔物质加入)。     

内蒙古中南部出露地壳元素丰度值的估算

运用区域大规模采样方法,对内蒙古中南部地区所采样品进行元素丰度值加权计算,这是建立区域地壳模型的基础工作之一,同时也为化探异常的检出提供较为准确的背景值。研究区涉及内蒙古地轴和内蒙古中部造山系2个构造单元。采用加权求平均值的方法,得到内蒙古中南部出露地壳10种常量元素氧化物和40种微量元素的丰度值。经地表热流值、地震平均波速和元素比值方法检验后证明所得结果合理。计算所得内蒙古中南部出露地壳平均成分为花岗闪长质,与目前一般认为的结论相同。将结果与其他地区进行比较分析后可知,内蒙古中南部出露的地壳与全球上地壳的组成基本一致。由微量元素、稀土元素的图解和内蒙古中南部出露地壳的元素丰度与中国东部出露地壳元素丰度的对比可以看出,整体上,内蒙古中南部具有较强的壳内分异作用和地壳增生作用(地幔物质加入)。     

大别造山带东段金铀钍的丰度系列,演化特征及与铀金成矿作…

本文列出了大别造山带东段各地质体、地壳各结构层及区域地壳的金、铀、钍丰度计算值，并根据大陆地壳的总体构成粗略估算出这三种元素的全球陆壳丰度。大别造山带地壳金明显富集且纵向分布较均匀，具有利的金成矿背景。铀的资源潜力则大为逊色，这是由于区内基底岩石成熟度低，陆壳发育晚，稳定程度差等因素决定的。根据各类丰度系数、元素的地史演化特征与成 质条件等因素分析，对该区铀金矿产勘查方向提出了几点建议。     

新疆北部火山岩及其与成矿的关系

新疆北部火山岩及其与成矿的关系梅厚钧，杨学昌，李荪蓉（中国科学院广州地质新技术研究所，广州５１０６４０）（ＧｕａｎｇｚｈｏｕＩｎｓｔｉｔｕｔｅｏｆＧｅｏｌｏｇｙａｎｄＮｅｗＴｅｃｈｎｏｌｏｇｙ，ＣＡＡＳ）（中国科学院贵阳地球化学研究所，贵阳５５０００...     

塔里木一华北板块的地壳和岩石圈元素丰度

塔里木－华北板块是我国境内最大的岩石圈板块,也是我国最重要的成矿区域之一。给出了本板块的地壳模型和岩石圈模型,并分别计算出本板块的地壳和岩石圈的元素丰度,讨论了本板块的主要丰度特征。     

湘南区域地层地球化学特征及其成矿意义

在系统统计湘南地区出露地层各类岩石成矿元素丰度，总体平均含量，浓度克拉克值和叠加强度参数基础上，结合湘南地区成矿特点，分析了Ｗ，Ｓｎ，Ｐｂ，Ｚｎ，Ｓｂ等元素的成矿作用，初步认为湘南地区仅沉积作用，海底火山作用及热卤水作用难以形成上述元素的大型矿床，但通过沉积改造，热液叠加作用有可能形成层控型铅，锌矿床和锑矿床。     

新疆北部地质演化及其与成矿的关系

新疆北部地质演化及其与成矿的关系胡霭琴，张国新，李启新，范嗣昆，张前锋（中国科学院广州地质新技术研究所，广州５１０６４０（ＧｕａｎｇｚｈｏｕＩｎｓｔｉｔｕｔｅｏｆＧｅｏｌｏｇｙａｎｄＮｅｗＴｅｃｈｎｏｌｏｇｙ，ＣＡＡＳ）（新疆维吾尔自治区地质矿产局第...     

浙江西裘铜块状硫化物矿床火山-热泉沉积成矿的地质地球化学证据

浙江西裘矿区新元古代火山－热泉活动强烈,矿石Ｃｕ：Ｚｎ：Ｐｂ原子百分比与火山岩和热水沉积硅质岩相似。矿床δ＾３４Ｓ值为－６．５‰～２．８‰,δ＾１８Ｏ值为８．１４‰～２２．３２‰,铅同位素示踪主要为下地壳铅;矿石具较高的Ａｓ、Ｓｂ、Ｂｉ、Ｇａ、Ｚｎ、Ｂａ等含量;具较低的Ａｌ／（Ａｌ＋Ｆｅ＝Ｍｎ）比值,Ｚｎ（Ｐｂ＋Ｚｎ）比值接近１,均表现出火山－热泉沉积成矿地球化学特征。     

塔里木—华北板块的地壳和岩石圈元素丰度

塔里木—华北板块是我国境内最大的岩石圈板块,也是我国最重要的成矿区域之一。给出了本板块的地壳模型和岩石圈模型,并分别计算出本板块的地壳和岩石圈的元素丰度,讨论了本板块的主要丰度特征     

KTB深部地壳实验室

德国大陆科学钻探计划的钻探了第二口超深孔,简要介绍了ＫＴＢ计划完成以后,在现场组建的深部地壳实验室的情况。     

Crustal Growth Rate of the North China Platform：a Method of Estimating Mass Equilibrium between Crust and Mantle

The following equation is proposed in this paper to estimate the crustal growth rate of the North China Platform on the basis of mass equilibrium between the crust and the mantle:

地壳运动的力源问题探讨

本文提出了一个假设,即地壳运动的力源主要是太空对地球的引力变化,并对地壳运动作了初步分析,提出了存在的问题和想法。     

冀西北地区晚太古代大陆地壳的增生和再造——同位素年代学证据

冀西北地区出露的太古宙变质岩系是华北地台北缘麻粒岩相带的重要组成部分。详细的同位素地质年代学研究表明，本区古老的地壳形成于２９００Ｍａ左右，为玄武质成分。古老地壳的熔融再造作用主要有两期，一期发生在２７８０～２７６１Ｍａ期间，产生了研究区西部广泛分布的英云闪长质片麻岩，另一期发生在２５６１～２５０３Ｍａ期间，形成在宣化－赤城一带广泛分布的花岗闪长质片麻岩。此后，在２５００～２４００Ｍａ期间发生了区域麻粒岩相变质改造，使部分岩石的同位素体系重新设置。     

基于GIS的中国区域地壳稳定性评价

在上世纪90年代杜东菊等人编制的“中国区域稳定工程地质图”的基础上,开发了中国区域地壳稳定性数据库,数据库存入了历史地震、活动断裂、地壳形变、活火山等大量内动力地质作用的信息。介绍了该数据库开发的方法,提出了加权信息量法评价模型,在GIS数据库平台上实现了用该模型对中国区域地壳稳定性进行评价。根据评价结果,按稳定、基本稳定、次不稳定、不稳定4个级别对中国陆域范围进行了地壳稳定性分区,作出了分区图,分区结果与实际吻合。     

Crustal structure of the Kaapvaal craton and its significance for early crustal evolution

High-quality seismic data obtained from a dense broadband array near Kimberley, South Africa, exhibit crustal reverberations of remarkable clarity that provide well-resolved constraints on the structure of the lowermost crust and Moho. Receiver function analysis of Moho conversions and crustal multiples beneath the Kimberley array shows that the crust is 35 km thick with an average Poisson's ratio of 0.25. The density contrast across the Moho is 15%, indicating a crustal density about 2.86 gm/cc just above the Moho, appropriate for felsic to intermediate rock compositions. Analysis of waveform broadening of the crustal reverberation phases suggests that the Moho transition can be no more than 0.5 km thick and the total variation in crustal thickness over the 2400 km² footprint of the array no more than 1 km. Waveform and travel time analysis of a large earthquake triggered by deep gold mining operations (the Welkom mine event) some 200 km away from the array yield an average crustal thickness of 35 km along the propagation path between the Kimberley array and the event. P- and S-wave velocities for the lowermost crust are modeled to be 6.75 and 3.90 km/s, respectively, with uppermost mantle velocities of 8.2 and 4.79 km/s, respectively. Seismograms from the Welkom event exhibit theoretically predicted but rarely observed crustal reverberation phases that involve reflection or conversion at the Moho. Correlation between observed and synthetic waveforms and phase amplitudes of the Moho reverberations suggests that the crust along the propagation path between source and receiver is highly uniform in both thickness and average seismic velocity and that the Moho transition zone is everywhere less than about 2 km thick. While the extremely flat Moho, sharp transition zone and low crustal densities beneath the region of study may date from the time of crustal formation, a more geologically plausible interpretation involves extensive crustal melting and ductile flow during the major craton-wide Ventersdorp tectonomagmatic event near the end of Archean time.     

川滇地区重力场特征与地壳变形研究

对川滇地区重力场特征进行了研究,获得了研究区内地壳厚度分布及变形特征。总体上,研究区内地壳厚度从西北向东南逐渐减小。川滇菱形块体中内部出现了广泛的地壳增厚现象,并可能一直延伸至菱形块体的最南端。丽江-小金河断裂带在重力场特征上表现为龙门山断裂带向西南的延伸,其东侧主体构造走向等特征与扬子地块一致,推测丽江-小金河断裂带与龙门山断裂、红河断裂带一起构成了扬子地块的西边界。滇西地区布格重力一阶导数与现今地壳变形格局总体一致,主体构造方向为北北西-近南北向,代表了“新”构造主体构造线的方向;上延至45km后,主体构造上转变为以近东西向为主。     

Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

There is an ongoing debate about the tectonic evolution of southeast Australia, particularly about the causes and nature of its accretion to a much older Precambrian core to the west. Seismic imaging of the crust can provide useful clues to address this issue. Seismic tomography imaging is a powerful tool often employed to map elastic properties of the Earth's lithosphere, but in most cases does not constrain well the depth of discontinuities such as the Mohorovi?i? (Moho). In this study, an alternative imaging technique known as receiver function (RF) has been employed for seismic stations near Canberra in the Lachlan Orogen to investigate: (i) the shear-wave-velocity profile in the crust and uppermost mantle, (ii) variations in the Moho depth beneath the Lachlan Orogen, and (iii) the nature of the transition between the crust and mantle. A number of styles of RF analyses were conducted: H-K stacking to obtain the best compressional–shear velocity (V _P /V _S) ratio and crustal thickness; nonlinear inversion for the shear-wave-velocity structure and inversion of the observed variations in RFs with back-azimuth to investigate potential dipping of the crustal layers and anisotropy. The thick crust (up to 48 km) and the mostly intermediate nature of the crust?mantle transition in the Lachlan Orogen could be due to the presence of underplating at the base of the crust, and possibly to the existing thick piles of Ordovician mafic rocks present in the mid and lower crust. Results from numerical modelling of RFs at three seismic stations (CAN, CNB and YNG) suggest that the observed variations with back-azimuth could be related to a complex structure beneath these stations with the likelihood of both a dipping Moho and crustal anisotropy. Our analysis reveals crustal thickening to the west beneath CAN station which could be due to slab convergence. The crustal thickening may also be related to the broad Macquarie volcanic arc, which is rooted to the Moho. The crustal anisotropy may arise from a strong N–S structural trend in the eastern Lachlan Orogen and to the preferred crystallographic orientation of seismically anisotropic minerals in the lower and middle crust related to the paleo-Pacific plate convergence.     

An abundance model resource appraisal for some Canadian commodities

An abundance model resource appraisal has been undertaken for 10 mineral commodities in Canada: nickel, copper, zinc, lead, molybdenum, uranium, silver, gold, chromium, and tin. The purpose of the appraisal was to investigate the applicability of the model to the Canadian situation. Resource appraisals for the first 6 of the commodities studied have been published following deposit modeling studies. For many other commodities studied have been published following deposit modeling appraisals. The demonstration of the relevance of the abundance model to Canada would allow its application in such cases. The data presented in this paper indicate that the approximate relation, resource (short tons)=abundance (%)×10¹⁰. holds true for all commodities studied except chromium and tin. As the resources versus abundances relationship observed on a global scale is observable in Canada, it is concluded that Canada is a sufficiently large fraction (∼7%) of the earth's continental crust to represent a valid sample of that crust. Canada appears to be relatively well endowed with resources of copper, molybdenum, lead, and zinc, and poorly endowed with chromium and tin. It is proposed that the intersection of national boundaries with the boundaries of the world's metallogenic provinces is of greater importance than the intensity of past search, a feature that has been suggested in other studies. If these areas overlap, a nation may be self sufficient in a commodity: if they do not, the nation must import, or find a nationally available substitute. The sources of information used in the appraisal are outlined together with an analysis of the problems encounterea and the time requirements. This paper was presented at the International Geological Correlation Program (IGCP) Project 98: “Standards for Computer Applications in Resource Studies” held at Taita Hills Kenya, November 8–15, 1977.     

金沙江溪洛渡水电站地应力测量

利用1999～2001年在金沙江溪洛渡水电站厂区用水压致裂法先后完成的9个垂直深钻孔平面地应力和8个测点三维应力测量结果，结合河谷地形地貌、构造岩性等资料，对工程区地应力场的基本特征进行了较系统的分析研究，认为电站区最大主应力数值在10～20MPa，方向在NW～NWW间，大致平行于金沙江河流走向，地应力作用以水平为主。随着深度增加，地层平面、三维主应力值均有所增大。本文的研究结果为电站工程设计提供了地应力的基础资料。